syscall.c

   1 /*
   2  * Syscall wrappers to ensure that nothing gets done in dry_run mode
   3  * and to handle system peculiarities.
   4  *
   5  * Copyright (C) 1998 Andrew Tridgell
   6  * Copyright (C) 2002 Martin Pool
   7  * Copyright (C) 2003-2022 Wayne Davison
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License as published by
  11  * the Free Software Foundation; either version 3 of the License, or
  12  * (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  * GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License along
  20  * with this program; if not, visit the http://fsf.org website.
  21  */
  22
  23 #include "rsync.h"
  24
  25 #if !defined MKNOD_CREATES_SOCKETS && defined HAVE_SYS_UN_H
  26 #include <sys/un.h>
  27 #endif
  28 #ifdef HAVE_SYS_ATTR_H
  29 #include <sys/attr.h>
  30 #endif
  31
  32 #if defined HAVE_SYS_FALLOCATE && !defined HAVE_FALLOCATE
  33 #include <sys/syscall.h>
  34 #endif
  35
  36 extern int dry_run;
  37 extern int am_root;
  38 extern int am_sender;
  39 extern int read_only;
  40 extern int list_only;
  41 extern int inplace;
  42 extern int preallocate_files;
  43 extern int preserve_perms;
  44 extern int preserve_executability;
  45 extern int open_noatime;
  46
  47 #ifndef S_BLKSIZE
  48 # if defined hpux || defined __hpux__ || defined __hpux
  49 #  define S_BLKSIZE 1024
  50 # elif defined _AIX && defined _I386
  51 #  define S_BLKSIZE 4096
  52 # else
  53 #  define S_BLKSIZE 512
  54 # endif
  55 #endif
  56
  57 #ifdef SUPPORT_CRTIMES
  58 #ifdef HAVE_GETATTRLIST
  59 #pragma pack(push, 4)
  60 struct create_time {
  61         uint32 length;
  62         struct timespec crtime;
  63 };
  64 #pragma pack(pop)
  65 #elif defined __CYGWIN__
  66 #include <windows.h>
  67 #endif
  68 #endif
  69
  70 #define RETURN_ERROR_IF(x,e) \
  71         do { \
  72                 if (x) { \
  73                         errno = (e); \
  74                         return -1; \
  75                 } \
  76         } while (0)
  77
  78 #define RETURN_ERROR_IF_RO_OR_LO RETURN_ERROR_IF(read_only || list_only, EROFS)
  79
  80 int do_unlink(const char *path)
  81 {
  82         if (dry_run) return 0;
  83         RETURN_ERROR_IF_RO_OR_LO;
  84         return unlink(path);
  85 }
  86
  87 #ifdef SUPPORT_LINKS
  88 int do_symlink(const char *lnk, const char *path)
  89 {
  90         if (dry_run) return 0;
  91         RETURN_ERROR_IF_RO_OR_LO;
  92
  93 #if defined NO_SYMLINK_XATTRS || defined NO_SYMLINK_USER_XATTRS
  94         /* For --fake-super, we create a normal file with mode 0600
  95          * and write the lnk into it. */
  96         if (am_root < 0) {
  97                 int ok, len = strlen(lnk);
  98                 int fd = open(path, O_WRONLY|O_CREAT|O_TRUNC, S_IWUSR|S_IRUSR);
  99                 if (fd < 0)
 100                         return -1;
 101                 ok = write(fd, lnk, len) == len;
 102                 if (close(fd) < 0)
 103                         ok = 0;
 104                 return ok ? 0 : -1;
 105         }
 106 #endif
 107
 108         return symlink(lnk, path);
 109 }
 110
 111 #if defined NO_SYMLINK_XATTRS || defined NO_SYMLINK_USER_XATTRS
 112 ssize_t do_readlink(const char *path, char *buf, size_t bufsiz)
 113 {
 114         /* For --fake-super, we read the link from the file. */
 115         if (am_root < 0) {
 116                 int fd = do_open_nofollow(path, O_RDONLY);
 117                 if (fd >= 0) {
 118                         int len = read(fd, buf, bufsiz);
 119                         close(fd);
 120                         return len;
 121                 }
 122                 if (errno != ELOOP)
 123                         return -1;
 124                 /* A real symlink needs to be turned into a fake one on the receiving
 125                  * side, so tell the generator that the link has no length. */
 126                 if (!am_sender)
 127                         return 0;
 128                 /* Otherwise fall through and let the sender report the real length. */
 129         }
 130
 131         return readlink(path, buf, bufsiz);
 132 }
 133 #endif
 134 #endif
 135
 136 #if defined HAVE_LINK || defined HAVE_LINKAT
 137 int do_link(const char *old_path, const char *new_path)
 138 {
 139         if (dry_run) return 0;
 140         RETURN_ERROR_IF_RO_OR_LO;
 141 #ifdef HAVE_LINKAT
 142         return linkat(AT_FDCWD, old_path, AT_FDCWD, new_path, 0);
 143 #else
 144         return link(old_path, new_path);
 145 #endif
 146 }
 147 #endif
 148
 149 int do_lchown(const char *path, uid_t owner, gid_t group)
 150 {
 151         if (dry_run) return 0;
 152         RETURN_ERROR_IF_RO_OR_LO;
 153 #ifndef HAVE_LCHOWN
 154 #define lchown chown
 155 #endif
 156         return lchown(path, owner, group);
 157 }
 158
 159 int do_mknod(const char *pathname, mode_t mode, dev_t dev)
 160 {
 161         if (dry_run) return 0;
 162         RETURN_ERROR_IF_RO_OR_LO;
 163
 164         /* For --fake-super, we create a normal file with mode 0600. */
 165         if (am_root < 0) {
 166                 int fd = open(pathname, O_WRONLY|O_CREAT|O_TRUNC, S_IWUSR|S_IRUSR);
 167                 if (fd < 0 || close(fd) < 0)
 168                         return -1;
 169                 return 0;
 170         }
 171
 172 #if !defined MKNOD_CREATES_FIFOS && defined HAVE_MKFIFO
 173         if (S_ISFIFO(mode))
 174                 return mkfifo(pathname, mode);
 175 #endif
 176 #if !defined MKNOD_CREATES_SOCKETS && defined HAVE_SYS_UN_H
 177         if (S_ISSOCK(mode)) {
 178                 int sock;
 179                 struct sockaddr_un saddr;
 180                 unsigned int len = strlcpy(saddr.sun_path, pathname, sizeof saddr.sun_path);
 181                 if (len >= sizeof saddr.sun_path) {
 182                         errno = ENAMETOOLONG;
 183                         return -1;
 184                 }
 185 #ifdef HAVE_SOCKADDR_UN_LEN
 186                 saddr.sun_len = len + 1;
 187 #endif
 188                 saddr.sun_family = AF_UNIX;
 189
 190                 if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0
 191                  || (unlink(pathname) < 0 && errno != ENOENT)
 192                  || (bind(sock, (struct sockaddr*)&saddr, sizeof saddr)) < 0)
 193                         return -1;
 194                 close(sock);
 195 #ifdef HAVE_CHMOD
 196                 return do_chmod(pathname, mode);
 197 #else
 198                 return 0;
 199 #endif
 200         }
 201 #endif
 202 #ifdef HAVE_MKNOD
 203         return mknod(pathname, mode, dev);
 204 #else
 205         return -1;
 206 #endif
 207 }
 208
 209 int do_rmdir(const char *pathname)
 210 {
 211         if (dry_run) return 0;
 212         RETURN_ERROR_IF_RO_OR_LO;
 213         return rmdir(pathname);
 214 }
 215
 216 int do_open(const char *pathname, int flags, mode_t mode)
 217 {
 218         if (flags != O_RDONLY) {
 219                 RETURN_ERROR_IF(dry_run, 0);
 220                 RETURN_ERROR_IF_RO_OR_LO;
 221         }
 222
 223 #ifdef O_NOATIME
 224         if (open_noatime)
 225                 flags |= O_NOATIME;
 226 #endif
 227
 228         return open(pathname, flags | O_BINARY, mode);
 229 }
 230
 231 #ifdef HAVE_CHMOD
 232 int do_chmod(const char *path, mode_t mode)
 233 {
 234         static int switch_step = 0;
 235         int code;
 236
 237         if (dry_run) return 0;
 238         RETURN_ERROR_IF_RO_OR_LO;
 239
 240         switch (switch_step) {
 241 #ifdef HAVE_LCHMOD
 242         case 0:
 243                 if ((code = lchmod(path, mode & CHMOD_BITS)) == 0)
 244                         break;
 245                 if (errno == ENOSYS)
 246                         switch_step++;
 247                 else if (errno != ENOTSUP)
 248                         break;
 249 #endif
 250                 /* FALLTHROUGH */
 251         default:
 252                 if (S_ISLNK(mode)) {
 253 # if defined HAVE_SETATTRLIST
 254                         struct attrlist attrList;
 255                         uint32_t m = mode & CHMOD_BITS; /* manpage is wrong: not mode_t! */
 256
 257                         memset(&attrList, 0, sizeof attrList);
 258                         attrList.bitmapcount = ATTR_BIT_MAP_COUNT;
 259                         attrList.commonattr = ATTR_CMN_ACCESSMASK;
 260                         if ((code = setattrlist(path, &attrList, &m, sizeof m, FSOPT_NOFOLLOW)) == 0)
 261                                 break;
 262                         if (errno == ENOTSUP)
 263                                 code = 1;
 264 # else
 265                         code = 1;
 266 # endif
 267                 } else
 268                         code = chmod(path, mode & CHMOD_BITS); /* DISCOURAGED FUNCTION */
 269                 break;
 270         }
 271         if (code != 0 && (preserve_perms || preserve_executability))
 272                 return code;
 273         return 0;
 274 }
 275 #endif
 276
 277 int do_rename(const char *old_path, const char *new_path)
 278 {
 279         if (dry_run) return 0;
 280         RETURN_ERROR_IF_RO_OR_LO;
 281         return rename(old_path, new_path);
 282 }
 283
 284 #ifdef HAVE_FTRUNCATE
 285 int do_ftruncate(int fd, OFF_T size)
 286 {
 287         int ret;
 288
 289         if (dry_run) return 0;
 290         RETURN_ERROR_IF_RO_OR_LO;
 291
 292         do {
 293                 ret = ftruncate(fd, size);
 294         } while (ret < 0 && errno == EINTR);
 295
 296         return ret;
 297 }
 298 #endif
 299
 300 void trim_trailing_slashes(char *name)
 301 {
 302         int l;
 303         /* Some BSD systems cannot make a directory if the name
 304          * contains a trailing slash.
 305          * <http://www.opensource.apple.com/bugs/X/BSD%20Kernel/2734739.html> */
 306
 307         /* Don't change empty string; and also we can't improve on
 308          * "/" */
 309
 310         l = strlen(name);
 311         while (l > 1) {
 312                 if (name[--l] != '/')
 313                         break;
 314                 name[l] = '\0';
 315         }
 316 }
 317
 318 int do_mkdir(char *path, mode_t mode)
 319 {
 320         if (dry_run) return 0;
 321         RETURN_ERROR_IF_RO_OR_LO;
 322         trim_trailing_slashes(path);
 323         return mkdir(path, mode);
 324 }
 325
 326 /* like mkstemp but forces permissions */
 327 int do_mkstemp(char *template, mode_t perms)
 328 {
 329         RETURN_ERROR_IF(dry_run, 0);
 330         RETURN_ERROR_IF(read_only, EROFS);
 331         perms |= S_IWUSR;
 332
 333 #if defined HAVE_SECURE_MKSTEMP && defined HAVE_FCHMOD && (!defined HAVE_OPEN64 || defined HAVE_MKSTEMP64)
 334         {
 335                 int fd = mkstemp(template);
 336                 if (fd == -1)
 337                         return -1;
 338                 if (fchmod(fd, perms) != 0 && preserve_perms) {
 339                         int errno_save = errno;
 340                         close(fd);
 341                         unlink(template);
 342                         errno = errno_save;
 343                         return -1;
 344                 }
 345 #if defined HAVE_SETMODE && O_BINARY
 346                 setmode(fd, O_BINARY);
 347 #endif
 348                 return fd;
 349         }
 350 #else
 351         if (!mktemp(template))
 352                 return -1;
 353         return do_open(template, O_RDWR|O_EXCL|O_CREAT, perms);
 354 #endif
 355 }
 356
 357 int do_stat(const char *path, STRUCT_STAT *st)
 358 {
 359 #ifdef USE_STAT64_FUNCS
 360         return stat64(path, st);
 361 #else
 362         return stat(path, st);
 363 #endif
 364 }
 365
 366 int do_lstat(const char *path, STRUCT_STAT *st)
 367 {
 368 #ifdef SUPPORT_LINKS
 369 # ifdef USE_STAT64_FUNCS
 370         return lstat64(path, st);
 371 # else
 372         return lstat(path, st);
 373 # endif
 374 #else
 375         return do_stat(path, st);
 376 #endif
 377 }
 378
 379 int do_fstat(int fd, STRUCT_STAT *st)
 380 {
 381 #ifdef USE_STAT64_FUNCS
 382         return fstat64(fd, st);
 383 #else
 384         return fstat(fd, st);
 385 #endif
 386 }
 387
 388 OFF_T do_lseek(int fd, OFF_T offset, int whence)
 389 {
 390 #ifdef HAVE_LSEEK64
 391 #if !SIZEOF_OFF64_T
 392         OFF_T lseek64();
 393 #else
 394         off64_t lseek64();
 395 #endif
 396         return lseek64(fd, offset, whence);
 397 #else
 398         return lseek(fd, offset, whence);
 399 #endif
 400 }
 401
 402 #ifdef HAVE_SETATTRLIST
 403 int do_setattrlist_times(const char *path, STRUCT_STAT *stp)
 404 {
 405         struct attrlist attrList;
 406         struct timespec ts[2];
 407
 408         if (dry_run) return 0;
 409         RETURN_ERROR_IF_RO_OR_LO;
 410
 411         /* Yes, this is in the opposite order of utime and similar. */
 412         ts[0].tv_sec = stp->st_mtime;
 413         ts[0].tv_nsec = stp->ST_MTIME_NSEC;
 414
 415         ts[1].tv_sec = stp->st_atime;
 416         ts[1].tv_nsec = stp->ST_ATIME_NSEC;
 417
 418         memset(&attrList, 0, sizeof attrList);
 419         attrList.bitmapcount = ATTR_BIT_MAP_COUNT;
 420         attrList.commonattr = ATTR_CMN_MODTIME | ATTR_CMN_ACCTIME;
 421         return setattrlist(path, &attrList, ts, sizeof ts, FSOPT_NOFOLLOW);
 422 }
 423
 424 #ifdef SUPPORT_CRTIMES
 425 int do_setattrlist_crtime(const char *path, time_t crtime)
 426 {
 427         struct attrlist attrList;
 428         struct timespec ts;
 429
 430         if (dry_run) return 0;
 431         RETURN_ERROR_IF_RO_OR_LO;
 432
 433         ts.tv_sec = crtime;
 434         ts.tv_nsec = 0;
 435
 436         memset(&attrList, 0, sizeof attrList);
 437         attrList.bitmapcount = ATTR_BIT_MAP_COUNT;
 438         attrList.commonattr = ATTR_CMN_CRTIME;
 439         return setattrlist(path, &attrList, &ts, sizeof ts, FSOPT_NOFOLLOW);
 440 }
 441 #endif
 442 #endif /* HAVE_SETATTRLIST */
 443
 444 #ifdef SUPPORT_CRTIMES
 445 time_t get_create_time(const char *path, STRUCT_STAT *stp)
 446 {
 447 #ifdef HAVE_GETATTRLIST
 448         static struct create_time attrBuf;
 449         struct attrlist attrList;
 450
 451         (void)stp;
 452         memset(&attrList, 0, sizeof attrList);
 453         attrList.bitmapcount = ATTR_BIT_MAP_COUNT;
 454         attrList.commonattr = ATTR_CMN_CRTIME;
 455         if (getattrlist(path, &attrList, &attrBuf, sizeof attrBuf, FSOPT_NOFOLLOW) < 0)
 456                 return 0;
 457         return attrBuf.crtime.tv_sec;
 458 #elif defined __CYGWIN__
 459         (void)path;
 460         return stp->st_birthtime;
 461 #else
 462 #error Unknown crtimes implementation
 463 #endif
 464 }
 465
 466 #if defined __CYGWIN__
 467 int do_SetFileTime(const char *path, time_t crtime)
 468 {
 469         if (dry_run) return 0;
 470         RETURN_ERROR_IF_RO_OR_LO;
 471
 472         int cnt = MultiByteToWideChar(CP_UTF8, 0, path, -1, NULL, 0);
 473         if (cnt == 0)
 474             return -1;
 475         WCHAR *pathw = new_array(WCHAR, cnt);
 476         if (!pathw)
 477             return -1;
 478         MultiByteToWideChar(CP_UTF8, 0, path, -1, pathw, cnt);
 479         HANDLE handle = CreateFileW(pathw, FILE_WRITE_ATTRIBUTES, FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,
 480                                     NULL, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, NULL);
 481         free(pathw);
 482         if (handle == INVALID_HANDLE_VALUE)
 483             return -1;
 484         int64 temp_time = Int32x32To64(crtime, 10000000) + 116444736000000000LL;
 485         FILETIME birth_time;
 486         birth_time.dwLowDateTime = (DWORD)temp_time;
 487         birth_time.dwHighDateTime = (DWORD)(temp_time >> 32);
 488         int ok = SetFileTime(handle, &birth_time, NULL, NULL);
 489         CloseHandle(handle);
 490         return ok ? 0 : -1;
 491 }
 492 #endif
 493 #endif /* SUPPORT_CRTIMES */
 494
 495 #ifdef HAVE_UTIMENSAT
 496 int do_utimensat(const char *path, STRUCT_STAT *stp)
 497 {
 498         struct timespec t[2];
 499
 500         if (dry_run) return 0;
 501         RETURN_ERROR_IF_RO_OR_LO;
 502
 503         t[0].tv_sec = stp->st_atime;
 504 #ifdef ST_ATIME_NSEC
 505         t[0].tv_nsec = stp->ST_ATIME_NSEC;
 506 #else
 507         t[0].tv_nsec = 0;
 508 #endif
 509         t[1].tv_sec = stp->st_mtime;
 510 #ifdef ST_MTIME_NSEC
 511         t[1].tv_nsec = stp->ST_MTIME_NSEC;
 512 #else
 513         t[1].tv_nsec = 0;
 514 #endif
 515         return utimensat(AT_FDCWD, path, t, AT_SYMLINK_NOFOLLOW);
 516 }
 517 #endif
 518
 519 #ifdef HAVE_LUTIMES
 520 int do_lutimes(const char *path, STRUCT_STAT *stp)
 521 {
 522         struct timeval t[2];
 523
 524         if (dry_run) return 0;
 525         RETURN_ERROR_IF_RO_OR_LO;
 526
 527         t[0].tv_sec = stp->st_atime;
 528 #ifdef ST_ATIME_NSEC
 529         t[0].tv_usec = stp->ST_ATIME_NSEC / 1000;
 530 #else
 531         t[0].tv_usec = 0;
 532 #endif
 533         t[1].tv_sec = stp->st_mtime;
 534 #ifdef ST_MTIME_NSEC
 535         t[1].tv_usec = stp->ST_MTIME_NSEC / 1000;
 536 #else
 537         t[1].tv_usec = 0;
 538 #endif
 539         return lutimes(path, t);
 540 }
 541 #endif
 542
 543 #ifdef HAVE_UTIMES
 544 int do_utimes(const char *path, STRUCT_STAT *stp)
 545 {
 546         struct timeval t[2];
 547
 548         if (dry_run) return 0;
 549         RETURN_ERROR_IF_RO_OR_LO;
 550
 551         t[0].tv_sec = stp->st_atime;
 552 #ifdef ST_ATIME_NSEC
 553         t[0].tv_usec = stp->ST_ATIME_NSEC / 1000;
 554 #else
 555         t[0].tv_usec = 0;
 556 #endif
 557         t[1].tv_sec = stp->st_mtime;
 558 #ifdef ST_MTIME_NSEC
 559         t[1].tv_usec = stp->ST_MTIME_NSEC / 1000;
 560 #else
 561         t[1].tv_usec = 0;
 562 #endif
 563         return utimes(path, t);
 564 }
 565
 566 #elif defined HAVE_UTIME
 567 int do_utime(const char *path, STRUCT_STAT *stp)
 568 {
 569 #ifdef HAVE_STRUCT_UTIMBUF
 570         struct utimbuf tbuf;
 571 #else
 572         time_t t[2];
 573 #endif
 574
 575         if (dry_run) return 0;
 576         RETURN_ERROR_IF_RO_OR_LO;
 577
 578 # ifdef HAVE_STRUCT_UTIMBUF
 579         tbuf.actime = stp->st_atime;
 580         tbuf.modtime = stp->st_mtime;
 581         return utime(path, &tbuf);
 582 # else
 583         t[0] = stp->st_atime;
 584         t[1] = stp->st_mtime;
 585         return utime(path, t);
 586 # endif
 587 }
 588
 589 #else
 590 #error Need utimes or utime function.
 591 #endif
 592
 593 #ifdef SUPPORT_PREALLOCATION
 594 #ifdef FALLOC_FL_KEEP_SIZE
 595 #define DO_FALLOC_OPTIONS FALLOC_FL_KEEP_SIZE
 596 #else
 597 #define DO_FALLOC_OPTIONS 0
 598 #endif
 599
 600 OFF_T do_fallocate(int fd, OFF_T offset, OFF_T length)
 601 {
 602         int opts = inplace || preallocate_files ? DO_FALLOC_OPTIONS : 0;
 603         int ret;
 604         RETURN_ERROR_IF(dry_run, 0);
 605         RETURN_ERROR_IF_RO_OR_LO;
 606         if (length & 1) /* make the length not match the desired length */
 607                 length++;
 608         else
 609                 length--;
 610 #if defined HAVE_FALLOCATE
 611         ret = fallocate(fd, opts, offset, length);
 612 #elif defined HAVE_SYS_FALLOCATE
 613         ret = syscall(SYS_fallocate, fd, opts, (loff_t)offset, (loff_t)length);
 614 #elif defined HAVE_EFFICIENT_POSIX_FALLOCATE
 615         ret = posix_fallocate(fd, offset, length);
 616 #else
 617 #error Coding error in SUPPORT_PREALLOCATION logic.
 618 #endif
 619         if (ret < 0)
 620                 return ret;
 621         if (opts == 0) {
 622                 STRUCT_STAT st;
 623                 if (do_fstat(fd, &st) < 0)
 624                         return length;
 625                 return st.st_blocks * S_BLKSIZE;
 626         }
 627         return 0;
 628 }
 629 #endif
 630
 631 /* Punch a hole at pos for len bytes. The current file position must be at pos and will be
 632  * changed to be at pos + len. */
 633 int do_punch_hole(int fd, OFF_T pos, OFF_T len)
 634 {
 635 #ifdef HAVE_FALLOCATE
 636 # ifdef HAVE_FALLOC_FL_PUNCH_HOLE
 637         if (fallocate(fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, pos, len) == 0) {
 638                 if (do_lseek(fd, len, SEEK_CUR) != pos + len)
 639                         return -1;
 640                 return 0;
 641         }
 642 # endif
 643 # ifdef HAVE_FALLOC_FL_ZERO_RANGE
 644         if (fallocate(fd, FALLOC_FL_ZERO_RANGE, pos, len) == 0) {
 645                 if (do_lseek(fd, len, SEEK_CUR) != pos + len)
 646                         return -1;
 647                 return 0;
 648         }
 649 # endif
 650 #else
 651         (void)pos;
 652 #endif
 653         {
 654                 char zeros[4096];
 655                 memset(zeros, 0, sizeof zeros);
 656                 while (len > 0) {
 657                         int chunk = len > (int)sizeof zeros ? (int)sizeof zeros : len;
 658                         int wrote = write(fd, zeros, chunk);
 659                         if (wrote <= 0) {
 660                                 if (wrote < 0 && errno == EINTR)
 661                                         continue;
 662                                 return -1;
 663                         }
 664                         len -= wrote;
 665                 }
 666         }
 667         return 0;
 668 }
 669
 670 int do_open_nofollow(const char *pathname, int flags)
 671 {
 672 #ifndef O_NOFOLLOW
 673         STRUCT_STAT f_st, l_st;
 674 #endif
 675         int fd;
 676
 677         if (flags != O_RDONLY) {
 678                 RETURN_ERROR_IF(dry_run, 0);
 679                 RETURN_ERROR_IF_RO_OR_LO;
 680 #ifndef O_NOFOLLOW
 681                 /* This function doesn't support write attempts w/o O_NOFOLLOW. */
 682                 errno = EINVAL;
 683                 return -1;
 684 #endif
 685         }
 686
 687 #ifdef O_NOFOLLOW
 688         fd = open(pathname, flags|O_NOFOLLOW);
 689 #else
 690         if (do_lstat(pathname, &l_st) < 0)
 691                 return -1;
 692         if (S_ISLNK(l_st.st_mode)) {
 693                 errno = ELOOP;
 694                 return -1;
 695         }
 696         if ((fd = open(pathname, flags)) < 0)
 697                 return fd;
 698         if (do_fstat(fd, &f_st) < 0) {
 699           close_and_return_error:
 700                 {
 701                         int save_errno = errno;
 702                         close(fd);
 703                         errno = save_errno;
 704                 }
 705                 return -1;
 706         }
 707         if (l_st.st_dev != f_st.st_dev || l_st.st_ino != f_st.st_ino) {
 708                 errno = EINVAL;
 709                 goto close_and_return_error;
 710         }
 711 #endif
 712
 713         return fd;
 714 }